Giles claimed 4 for 52 while Cosker grabbed 3 for 46 as the pair bowled virtually unchanged in tandem as Sri Lanka lost their last nine wickets for 101 runs.
England made a disastrous start to their reply with the captain, Nick Knight, being trapped lbw by Ruchira Perera with the third ball of the innings but Steve James finished unbeaten on 23 while Darren Maddy continued his prolific form by reaching the close on 22.
England A will take advice from government officials following another fatal bomb blast in Colombo yesterday. The tour manager, Graham Gooch, is to discuss the situation with the British High Commission today after the Tamil Tigers terrorist group exploded a bomb in the country's capital which killed seven people.
It follows a previous attack in Kandy on the famous Temple of the Tooth which resulted in 13 deaths and prompted a revision to the original itinerary, cutting the tour short by 10 days.
Sri Lanka A won toss; first day of four
SRI LANKA A - First Innings
*R P Arnold c Nash b Hutchison 15
A Gunawardena c knight b Giles 51
N Nawaz c and b Giles 5
D R M Jayawardene c Knight b Cosker 6
M C Mendis c and b Cosker 58
I de Seram c Maddy b Cosker 5
P B Dassanayake c Knight b Giles 2
H Boteju c Ealham b Hollioake 10
N Bandartilleke not out 10
R Perera c Nash b Giles 4
A Juniad b Hutchison 1
Extras (lb1, w1, nb2) 4
Total (72.3 overs) 171
Fall: 1-43, 2-70, 3-81, 4-85, 5-97, 6-114, 7-155, 8-157, 9-162.
Bowling: Hutchison 7.3-3-25-2; Hollioake 6-1-29-1; Brown 7-2-18-0; Giles 26-7-52-4; Cosker 26-11-46-3.
ENGLAND A - First Innings
S P James not out 23
*N V Knight lbw b Perera 0
D L Maddy not out 22
Extras (lb1, w1) 2
Total (for 1, 16 overs) 47
To bat: M A Ealham, D J G Sales, B C Hollioake, D R Brown, A F Giles, D C Nash, D A Cosker, P M Hutchison.
Bowling: Perera 3-0-16-1; Boteju 5-1-6-0; Bandartilleke 5-1-9-0; Juniad 2-0-11-0; Arnold 1-0-4-0.
Umpires: R N S Sirasona and T H Wijewardena.Reuse content